I would not put lime in under any circumstances, the manufacturer recommends never adding lime to ciment fondu.

You are truely opening a can of worms making your own castable mixture. If you visit a refractory, they will sell you the castable mix you need to cast your own oven.

During a visit to my local refractory, I spoke with the owner and his engineer about a home made castable for my best friend working overseas where materials are not readily available. This is the home brew recipe they gave me -use at your own risk:

In the mean time can you or someone else tell me what you use the lime for in this mix? I was under an uneducated assumption that the Ciment Fondu was a complete refractory cement solution.

My interest is in using The Ciment Fondu or HeatStop 50 or any similar product for a self cast oven, most likely in several pieces.

I wonder if it would be acceptable to add the sand and/or some clay to the refractory cement in self cast pieces for a WFO? The idea being to get some more product for the oven pieces at a lower price. Or would the sand and clay weaken the pieces too much for self standing cast oven pieces?

Thanks for any comments or wisdom on materials and methods.

John
Merrill, WI

PS I think my local Cement provider has quoted me $68.00 for what they are calling a 40 pound pail of HeatStop II, (that seems kind of high and I haven't seen reference to a 40 pound package anywhere else).

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JGestner,
What you are chasing is known in the trade here as castable refractory. As Lburou advised creating your own brew is risky, i"d stick with a ready mixed product, it may be more expensive , but at least you know it will work properly. There are all kinds of goodies they put in the mix to make it perform.

Yes I am starting to understand that calcium aluminate would need to be mixed with the proper measures of aggregates to create a dependable castable refractory material.

I am just trying to find all of the different acceptable materials, premixed or not, to use for casting oven pieces.

Then which are available to me in the middle of Wisconsin.

And then it would be nice if it was less expensive than what my local Concrete company quoted me, ($68 US /64.688 AUD for 40 LB/ 18.1 Kilo Pail of HeatSet II).

More research is cheaper than jumping in with what I have been offered as of today. I also have a suspicion that many different companies are selling many products that might work just fine, but all at different prices and availabilities to me.

Thanks for any insight, I need a lot more before I jump into this project.

I have been down the same road. The manufacturers like to keep their recipes secret so finding out the actual recipe is difficult. They use fired crushed clay which will not shrink like unfired clay. This is an advantage because when you cast, depending on how you have set up your mould there will be virtually no shrinkage.They use fly ash, one characteristic this gives is to make the mix more fluid during work up so you don't need so much water addition. They use fibres which burn out at 160 C, so you are left with tiny pipes that water can escape from during curing to avoid blowing.Who knows what else is the brew? You would need to add these ingredients in the correct proportions too. It would take you ages to mix all this stuff up. I find it is easier to buy the stuff premixed.At least you know it will work.

Heatstop II is a great mortar, but it is NOT a castable refractory. If someone told you that it was I would look for a different, more knowledgeable source. Heatstop does sell a 40# bag of castable, but it is not the same as HSII.

Thanks guys
The more I get into this, the less I know! Hope that changes sometime fairly soon.
The lack of local vendor knowledge issue seems to be a sore point. I may be trying to build the first WFO in my north central Wisconsin county.

Wonderful
I look up HeatStop 40 and the first site I see a price for says "Heat Cast-40
Castable refractory used to form and pour special shapes, hearth or oven dome.
HC40 Heat Cast-40 (40# bag) ................. $51.88 plus $39.00 shipping

HC40 Heat Cast-40 (40# bag) - $90.88"

At this rate I might just go dig my own clay and do a straw mud oven for zero cost solution that might last just more than a year with a lot of babying.

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